The present invention relates to an apparatus for the production of back-foamed cushions, in particular, for motor vehicle seats. The apparatus broadly comprises a mold with associated mixing head, in which an upper ram is provided above the lower mold half. Either or both of the lower mold half and the upper ram are movable towards each other.
It is known to push the piece of cover material into the mold cavity by means of an upper ram and/or a vacuum. If the bottom of the mold cavity is heavily contoured, the material may fail to make firm contact with the base of the cavity at every point. This is especially true if the cover material is not capable of stretching. This is liable to happen even if a vacuum is applied to the mold cavity to suck the material into contact with the mold cavity (DE OS No. 27 46 686) because the force of suction may be insufficient in areas with small radii (for example, at the base of projections at the bottom of the mold cavity). More powerful suction, however, would damage the cover material. At the same time, the piece of cover material must have the opportunity to move from a point, generally the center of the mold cavity, so that it can be stretched out. It is absolutely necessary to prevent the formation of unwanted folds or creases. The problem then arises of improving the apparatus mentioned above so that the piece of cover material will be smoothly placed against the wall of the mold at every point, and in particular at the bottom of the mold cavity, even when the interior surface of the mold is contoured with projections or ridges or the like.